Unanswered: ExtJs 4.0.2a / 4.0.7 - Charting

Unanswered: ExtJs 4.0.2a / 4.0.7 - Charting

I have a Tabpanel with a panel (containing a chart and a grid) inside each tab. In 4.0.2a I had all charts rendered in Firefox and Chrome. In 4.0.7 chrome wouldn't render the content of the tabs(charts and grids), -> white page.
As well, in 4.0.2a the charts do render correct on the initial load, if the store's data has changed, the hidden tabs render incorrect, I guess as the sizes of the charts are gone. Therefore only the axis labels are rendered.
The console is showing errors like:
"Unexpected value NaN parsing x attribute." I think for each SVG vector.

Is there a way to prevent this? I tried specifing explicit height and width of the chart, but didn't change anything.
Any idea's?
Cheers,
Pete

Yes the data is correct as it is displayed at the first time, only when the store is reloaded I get the problem for tabs which are not displayed at the time.
And actually I just discovered that the SVG is important, cause...

... as you see, the vectors are there, but I just realized that all of the classes attributes are set to:
class=" x-hide-visibility"

I don't know why, but if I change this classes in Firebug, this elements become visible. So the question is why Ext is setting this classes to a hide mode one.